1. Field of the Invention
This invention relates to an apparatus and method for treatment of laundry with ozone, and more particularly, to a variable system for treatment of laundry that is capable of delivering different measured amounts of dissolved ozone concentrations to multiple washing machines.
2. Description of the Background Art
Commercial laundry facilities consume large amounts of chemicals, energy and water during wash cycles. Additionally, a byproduct of commercial laundry facilities is generation of wastewater that must be monitored and treated prior to disposal. A typical laundry facility may consist of multiple single washing machines or continuous load washers (i.e., tunnel washers), or a combination thereof. By way of example, a xe2x80x9ctypicalxe2x80x9d commercial laundry facility may include multiple single washing machines that may be from 50 to 600-pound capacity. If a laundry facility consists of four 600-pound and two 100-pound single washers, the yearly production of the facility based on three shifts a day may exceed 12 million pounds. The type of laundry or laundry processed may include, but is not limited to, white and colored towels and bed linens, table clothes, bath mats, blankets and medical supplies. Generally, the type of laundry processed imposes a specific chemical formula that ordinarily includes one or more of the following: detergent, alkali, bleach, anti-bleach, sour and fabric softener. There are generally several filling and draining cycles associated with each wash cycle. If it is necessary to treat for impurities (i.e., filtration of lint) and/or adjust the pH of the wash wastewater prior to disposal, additional chemicals such as sulfuric acid and sodium hydroxide may be required.
There presently exist many types of apparatus and method to treat laundry and wash wastewater with ozone. Ozone may be used to substitute for or to augment detergent use since ozone is a powerful bleaching and oxidizing agent. Utilization of ozone in the laundry process can reduce energy consumption since no hot water is required, save or eliminate chemicals which are potentially harmful to the environment, reduce water consumption and reduce wastewater generation. Consequently, use of ozone in the laundry process can even reduce the time required to wash a load of laundry and therefore reducing the labor and energy costs. The production of ozone is well known in the art and is typically produced using either air or concentrated oxygen. However, prior approaches to treat laundry and wash wastewater with ozone have had limited commercial success for a variety of reasons.
By way of example, previous approaches of laundry ozone systems may inject wash water that is pumped out of a washer, including detergent, with ozone and then pump the wash water back into the washer for the duration of the wash cycle. There are several disadvantages to this approach. First, the detergent present in the wash water will consume the injected ozone almost instantaneously. Secondly, the ozone generator must work full time. Third, there is no mechanism to monitor the amount of ozone that is actually dissolved in the wash water to ensure that the laundry receives a preset level of ozone per wash cycle.
A second approach common in the prior art is for the used wash water to be collected in a tank (typically after it goes through a filtration process or is being recycled). The wash water is then circulated within the tank in which ozone is injected then pumped to the washers"" supply tank to maintain water levels. The disadvantage of this approach is the washer may receive inadequately ozonated wash water.
A third approach common in the prior art is to inject generated ozone directly into the washer after the washer is filled with water. The washer typically controls the ozone generator such that when the washer starts, it will activate the ozone generator and the ozone generator will start producing and introducing ozone directly into the washer. A disadvantage of this approach is that modification of the washer is necessary to incorporate a gas feed line into the tub of the washer. Additionally, not all washing machines (i.e., tunnel washers) can be readily modified with gas lines or would require a plurality of ozone gas feed lines.
In summary, previous attempts or teachings for treating for washing laundry with ozone have not provided a mechanism by which there is enough dissolved ozone available in the wash water to meet the demand of the soiled laundry. Specifically, previous systems typically furnish low levels of ozone. Nor have previous methods or apparatus provided a mechanism by which an operator may set and adjust the level of dissolved ozone to match the demand of the laundry. Prior art systems provide no control over the concentration of ozone, no means by which an operator can readily ascertain how much ozone is delivered and whether or not the delivered ozone is consumed by the ozone demand contaminant(s).
Continuing efforts are being made to improve laundry and laundry wastewater apparatus and methods. By way of example, note U.S. Pat. No. 5,493,743 to Schneider et al.; and U.S. Pat. Nos. 5,241,720, 5,181,399 and 5,097,556 to Engel et al. U.S. Pat. No. 5,493,743 discloses an apparatus and method for ozone assisted laundry washing and a wastewater treatment system which preferably is a xe2x80x9cclosed loopxe2x80x9d system which incorporates a process of tiered filtration whereby spent wash water may be collected, filtered and reused. The apparatus and method of Schneider et al. does not teach a mechanism by which an operator may readily select the level of dissolved ozone, and different concentrations of dissolved ozone may be delivered to multiple washing machines. Similarly, U.S. Pat. Nos. 5,241,720, 5,181,399 and 5,097,556 to Engel et al. teach non-adjustable closed loop systems. These patents disclose to add ozone to the wash water prior to use in a washing machine. The disclosure and teachings of these patents are incorporated herein by reference in their entirety.
U.S. Pat. No. 5,625,915 to Radler at al. discloses a complex laundry ozone injection system that utilizes an ozone manifold with a plurality of manifold outlets to deliver ozone. This patent discloses to modify the washer by allowing the water to be pumped out of the washer, injected with ozone, and pumped back into the washer. The disclosure of this patent is incorporated hereby reference in its entirety.
U.S. Pat. No. 5,409,616 to Garbutt et al. discloses a gray water reclamation system to treat and restore cleaning water in a closed loop, recyclable water system.
Another grouping of background patents are those which disclose treatment of wash wastewater. By way of example, see U.S. Pat. No. 5,787,537 to Mannillo which teaches a method to treat wastewater in a closed loop, wash system where ozone is used for purification of the water but not for the actual laundry cleaning process. Ozone is removed by ultraviolet light prior to the water being used to actually clean laundry.
Another grouping of background patents are those which disclose modifications to washing machines or filtration devices. Note U.S. Pat. No. 5,653,129 to Jang that discloses a mechanism by which ozone may be injected directly into the washing means. See also U.S. Pat. No. 5,765,403 to Lincoln et al.; U.S. Pat. No. 5,374,356 to Miller et al.; and U.S. Pat. No. 5,645,608 to Cooper et al.
Another grouping of background patents are those which disclose water formulations. Note U.S. Pat. No. 5,763,382 to Cooper et al. and U.S. Pat. No. 5,511,264 to Nishioka et al.
Not withstanding the existence of such prior art laundry apparatus and methods, there is a need for an improved and more efficient apparatus and method for the treatment of laundry that will achieve the requisite level of cleaning without having deleterious effects on the environment.
Therefore, it is an object of this invention to provide an improvement that overcomes the aforementioned inadequacies of the prior art devices and provides an improvement that is a significant contribution to the advancement of the laundry art.
It is an object of the present invention to provide a laundry treatment apparatus and method which permits the introduction of high levels of dissolved ozone (greater than 1.0 PPM) into the wash water.
It is an object of the present invention to increase the efficiency and flexibility of the utilization of ozone in the laundry process and permit an operator to set the concentration level of dissolved ozone concentration delivered to the washing machines. Furthermore, the laundry treatment apparatus and method of the present invention can deliver multiple concentration levels of ozonated water to different washing machines concurrently.
Another object of this invention is to provide a laundry treatment apparatus and method that is self-monitoring and maintains the selected level of dissolved ozone for delivery to the washing machines.
Another object of this invention is to provide a laundry treatment apparatus and method which eliminates the need for chemicals and additives such as bleach, Anti-Chlor (anti-bleach), sour and fabric softener.
Another object of this invention is to provide a laundry treatment apparatus and method that greatly reduces the amount of detergent and alkali used in the laundry process.
Another object of this invention is to provide a laundry treatment apparatus and method that greatly reduces the amount of water usage.
Another object of this invention is to provide a laundry treatment apparatus and method that greatly reduces labor and energy costs thereby increasing productivity due to reduction in wash cycle time.
Another object of this invention is to provide a laundry treatment apparatus and method that permits flexibility in setting the desired dissolved ozone concentration and maintains the desired concentration continually so long as the system is in operation.
Another object of this invention is to provide a laundry treatment apparatus and method that is capable of attaining a higher or lower level of dissolved ozone upon adjustment in a matter of minutes.
The foregoing has outlined some of the pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.
For the purpose of summarizing this invention, this invention comprises a treatment apparatus and method that greatly increases the efficiency and flexibility in using ozone in the laundry process by permitting an operator to set the level of dissolved ozone concentration delivered to the washing machines, depending upon the amount and type of soil on the laundry. Furthermore, the present invention ensures that there is enough dissolved ozone available in the wash water to meet the demand of the washing apparatus. Lastly, the present invention monitors and maintains the desired amount of dissolved ozone to be delivered to the washers.
As used herein, the term xe2x80x9claundryxe2x80x9d shall mean all washable fabrics and items. The apparatus and method of the present invention is drawn to an apparatus which incorporates an ozone system which serves as a water purification means, a supply tank and a transfer tank in fluid flow communication with multiple washing machines. The dissolved ozone level is monitored and controlled at a set point in the supply tank while the oxidation reduction potential (ORP) is monitored and controlled in the transfer tank. In operation, the apparatus of the present invention monitors the water levels in the supply and transfer tanks and automatically fills both tanks to the proper level and maintains the tanks full. When the tanks are full, the water in the supply tank is circulated between the supply tank and the ozone system until the desired ozone set point is reached. At this point, the water in the transfer tank is circulated until the ORP set point is reached. When both control parameters are reached, the ozone system will automatically shut off. The system will automatically turn on and the cycle will be repeated when the water level in the supply tank drops or the ozone level in either tank drops. A feed pump independent of the ozone system circulation loop, provides ozonated water (at the predetermined ozone level) to the washers on demand. More specifically, when the apparatus of the present mechanism senses a water demand, ozonated water will be supplied from the supply tank to the washer(s) and pre-treated water from the transfer tank will be pumped to the supply tank. The method of the present invention will continue automatically as long as there is a demand for water or ozone in either supply or transfer tank.
The key to successfully utilizing ozone in the laundry process is to ensure sufficient dissolved ozone in the wash water to meet demand from the washing machine(s). It is not sufficient to simply generate xe2x80x9cmorexe2x80x9d or higher levels of ozone gas, rather, it is necessary to ensure that the ozone goes into solution and is maintained at a constant concentration. The apparatus and method of the present invention permits flexibility in setting the desired dissolved ozone concentration and permits the simultaneous delivery of different dissolved ozone concentrations to multiple washers. Once the operator sets the desired concentration, it will be maintained continually by the system so long as the system is in operation. If for some reason the operator needs to adjust to a higher or lower level of dissolved ozone, it can be done readily and the system will achieve the new dissolved ozone concentration in a matter of minutes. Via a control system, preferably a programmable logic controller (PLC), the present invention provides the ability to continuously monitor the concentration of the dissolved ozone being delivered to the washing machine(s). As a safety feature, in use the apparatus and method of the present invention will deactivate the washing machine""s supply pump if the concentration of dissolved ozone is below the operator""s set point.
In use the present apparatus and method should greatly reduce the amount of detergent and alkali necessary to clean even the most soiled laundry. Based upon initial pilot study information, no hot water is required to operate the laundry apparatus, and detergent usage will be reduced on average of 50-70%. Consequently, the number of required rinses may be reduced by 35-40% which can result in a 35-40% water/sewer savings. The reduction in the number of required rinses can also reduce the duration of the wash cycle between 30-40%. Additionally, based upon initial pilot study information, the present apparatus and system will completely eliminate the need for pH adjustment.
The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description of the invention which follows may be better understood so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.